title: The NADH oxidase from the thermoacidophilic archaea Acidianus ambivalens: isolation and physicochemical characterisation.
abstract: A flavoprotein with NADH oxidising activity (NADH: acceptor oxidoreductase) was isolated from the soluble fraction of the thermoacidophilic archaea Acidianus ambivalens. The protein is a monomer with a molecular mass of 70 kDa and contains FAD as single cofactor. Its activity as NADH:O2 oxidoreductase is FAD, but not FMN, dependent and yields hydrogen peroxide as the reaction product. The activity decreases with pH in the range 4.5 to 9.8, and increases with the temperature, as tested from 30 degrees to 60 degrees C. As elicited by EPR, the purified enzyme also acts as an NADH:ferredoxin oxidoreductase. These features are discussed in light of the possible involvement of this protein in the metabolism of this archaea.
authors.affiliation: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: C M
authors.initials: CM
authors.lastname: Gomes
authors.forename: M
authors.initials: M
authors.lastname: Teixeira
mesh_terms: D005420:Flavoproteins / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry*; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry*; D010088:Oxidoreductases / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D016943:Sulfolobaceae / Q000201:enzymology*; D013696:Temperature
chemical_list: D005420:Flavoproteins; D009097:Multienzyme Complexes; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; C028878:ferredoxin-NAD+ reductase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D010100:Oxygen